Hypocholesterolemic drugs AY9944 and Triparanol produce neuronal as well as glial inclusions which are identical to those found in the neuronal lipid storage disease of human. In addition prominent degeneration of oligodendroglia and myelin were observed in the brain of the animals treated with these drugs at the time of myelination. The purpose of the proposed work is to study whether the degeneration of oligodendroglia and myelin degeneration are the unique phenomenon caused by hypocholesterolemic action of the drugs or common degenerative manifestation caused by the drugs which produce neuronal inclusions such as chloroquine, chlorphentermine, etc. Effect of the neuronal storage on development of axons and myelin and effect of these drugs on the fetal development will be also studied. Bibliographic references: Schaumburg, H.H., Powers, J.M., Raine, C.S., Suzuki, K. and Richardson, E.P.: Review of adreno-leukodystrophy, - A clinical and pathological study of seventeen cases. Arch. Neurol. 32-577-591, 1975. Igarashi, M., Suzuki, K., Chen, S.M. and Suzuki, K.: Hydrolytic enzymes in brains of young rats treated with cholesterol biosynthesis inhibitor AY9944. Brain Res. 90:97-114, 1975.